This invention relates to a gas cartridge or cylinder of the type which is used to charge a vessel with gas. The invention more particularly relates to a valve mechanism for a re-fillable gas cartridge or cylinder of this type.
One kind of vessel which is charged by means of a gas cartridge is commonly referred to as a soda siphon. However, the gas cartridges with which the invention is concerned are not intended exclusively for use on soda siphons. They may also be used in association with a carbonating head for carbonating the contents of a conventional plastics beverage container, commonly known as a PET bottle. The gas cartridges of the invention are also not confined to the generation of carbonated water. In some applications they are used for the manufacture of whipped cream and similar confections.
The gas cartridges of the invention may furthermore be used for charging play guns which are used to a growing extent in games in which participants fire paint filled gelatine capsules at one another.
It is known to employ gas cartridges of the aforementioned kind which are re-chargeable for repeated use. Such cartridges require a valve mechanism. One such valve mechanism has a rubber washer which is used to create a seal between a valve head of the mechanism and a valve seat. The rubber washer has not, however, proved to be entirely satisfactory. With repeated use, the rubber washer may become distorted, which may affect its sealing ability. Because of the very high pressure in the gas cartridge, usually of the order of 1000 to 12000 psi, the rubber washer may also display a tendency to extrude past the valve seat, which can lead to the destruction of the washer. It has also been found that the rubber washer does not always lift clearly off the valve seat when the valve mechanism is opened,with the result that an unimpeded discharge of gas from the cartridge is not obtained. In order to improve the gas discharge, a slot has been provided in the valve plunger carrying the valve head but this requires an additional machining operation on the valve plunger which adds to its cost.
It is accordingly an object of the invention to provide a valve mechanism for a re-fillable gas cartridge with which the abovementioned disadvantages are at least diminished.